Hydraulic Thumb on BH77

[awesome]

I've seen a few post where people talk about how to rig this up. I think I get the idea, but I'd like it if someone could confirm that this design is safe:
Edit: I mean "bote", not "stroke"

2" bore is ok? I should I go 3"
I understand the 2 pressure reliefs are required to avoid building too much pressure on the thumb. Is this what people are talking about?
A foot pedal would be better, but I already have an unused valve that I can repurpose for this.
Of course, I will also need to think about how to do proper routing to make sure I don't get a mess of hoses that can be ripped out.
Anything obvious I should be aware of?
Thanks for the help.

 

[TheOldHokie]

I've seen a few post where people talk about how to rig this up. I think I get the idea, but I'd like it if someone could confirm that this design is safe:

View attachment 151897
2" stroke is ok? I should I go 3"
I understand the 2 pressure reliefs are required to avoid building too much pressure on the thumb. Is this what people are talking about?
A foot pedal would be better, but I already have an unused valve that I can repurpose for this.
Of course, I will also need to think about how to do proper routing to make sure I don't get a mess of hoses that can be ripped out.
Anything obvious I should be aware of?
Thanks for the help.

A BH77 hoe does not have a power beyond port. It has two connections to the tractor - pressure in and tank return.

The port reliefs typically have 3 ports and simply go in line with the cylinder - no need for tees and additional hoses.

Dan

 

[PoTreeBoy]

I've seen a few post where people talk about how to rig this up. I think I get the idea, but I'd like it if someone could confirm that this design is safe:

View attachment 151897
2" stroke is ok? I should I go 3"
I understand the 2 pressure reliefs are required to avoid building too much pressure on the thumb. Is this what people are talking about?
A foot pedal would be better, but I already have an unused valve that I can repurpose for this.
Of course, I will also need to think about how to do proper routing to make sure I don't get a mess of hoses that can be ripped out.
Anything obvious I should be aware of?
Thanks for the help.

Looks good, but I doubt 2", or even 3", stroke will be sufficient. Do you have the thumb and mounting point mounted?

Edit: I thought the 77 had a T connection. If not, your new valve needs to go before the backhoe valve.

 

[TheOldHokie]

Looks good, but I doubt 2", or even 3", stroke will be sufficient. Do you have the thumb and mounting point mounted?

Edit: I thought the 77 had a T connection. If not, your new valve needs to go before the backhoe valve.

The BH77 has pressure in and tank return, This plumbing is similar to a loader third function. It will work on both a BH77 and BH70 and is much simpler than trying to use a valve with power beyond, You can gang the pressure reliefs together with a tee and mount it on the frame of the hoe. The electric valve also allows you to put a switch on one of the BH joysticks so you can operate the thumb without taking your hands off the joysticks.

Dan

 

[Smokeydog]

The M59 foot pedal never felt right. Added cleats that helped. Also added hand control rod that helped with delicate handing like stacking rocks. Hand control is more intuitive to me but probably a personal preference. Mention as hand control might be easier to fab

Funny the B26 thumb pedal though very similar is more ergonomic OEM design.

Once you experience a thumb, you’ll wonder how you did without.

 

[OntheRidge]

Just as a reference, the stroke on my thumb ram is 17". Bigger bh, yes.

 

[awesome]

Sorry, I meant Bore, and not Stroke.

 

[TheOldHokie]

Sorry, I meant Bore, and not Stroke.

That seemed obvious.

Dan

 

[fried1765]

The M59 foot pedal never felt right. Added cleats that helped. Also added hand control rod that helped with delicate handing like stacking rocks. Hand control is more intuitive to me but probably a personal preference. Mention as hand control might be easier to fab

Funny the B26 thumb pedal though very similar is more ergonomic OEM design.

Once you experience a thumb, you’ll wonder how you did without.

Same is true for a ZT mower!

 

[awesome]

The BH77 has pressure in and tank return, This plumbing is similar to a loader third function. It will work on both a BH77 and BH70 and is much simpler than trying to use a valve with power beyond, You can gang the pressure reliefs together with a tee and mount it on the frame of the hoe. The electric valve also allows you to put a switch on one of the BH joysticks so you can operate the thumb without taking your hands off the joysticks.

Dan

View attachment 151910

Isnt this a PB port that goes from the solenoid valve to the bh77 valve?
Also, no tank return on the solenoid valve?

 

[TheOldHokie]

Isnt this a PB port that goes from the solenoid valve to the bh77 valve?
Also, no tank return on the solenoid valve?

The solenoid valve has a pressure IN and a tank OUT. The tank port is rated for 3000 PSI so it can be safely used to supply full system pressure to a downstream valve. Technically its not a power beyond port which in an open center system separates the outflow into independent high (neutral) pressure and low (tank) pressure circuits. Thats more than just semantics. There are functional differences in the way return oil from the cylinders is routed. In this case it puts the thumb cylinder in series with the inlet port on the BH valve. A typical PB valve puts it in parallel. Its a geeky distinction but important to understand.

Dan

 

[awesome]

The solenoid valve has a pressure IN and a tank OUT. The tank port is rated for 3000 PSI so it can be safely used to supply full system pressure to a downstream valve. Technically its not a power beyond port which in an open center system separates the outflow into independent high (neutral) pressure and low (tank) pressure circuits. Thats more than just semantics. There are functional differences in the way return oil from the cylinders is routed. In this case it puts the thumb cylinder in series with the inlet port on the BH valve. A typical PB valve puts it in parallel. Its a geeky distinction but important to understand.

Dan

I think I understand.
But I will want to use my manual control valve since I already have one. In this case, I will need the PB on the valve right? I don't see how it would work otherwise.

So while I am not touching the valve, pressure will be maintained on both sides of the cylinder. But the relief valves would be triggered if I curl against the thumb.

 

[TheOldHokie]

I think I understand.
But I will want to use my manual control valve since I already have one. In this case, I will need the PB on the valve right? I don't see how it would work otherwise.

So while I am not touching the valve, pressure will be maintained on both sides of the cylinder. But the relief valves would be triggered if I curl against the thumb.

If your valve is a typical monoblock you will need to plumb both power beyond and tank returm circuits.

The port reliefs will operste any time pressure in the work circuit exceeds the pressure setting . Typically the rod end relief is set higher than the base end and both are higher than the main system pressure.

Dan